Electric switching apparatus

ABSTRACT

In an electric switching apparatus an energy accumulator switches the apparatus on or off by movement of a movable member to and from a stationary member. A switching-off spring associated with the energy accumulator is cocked in a switchingon state and is released with the uncoupling of a magnetic locking means mounted between the movable member and the stationary member and including magnetic operating means and an armature plate retained by the magnetic operating means in the switched-on state of the switching apparatus. The magnetic locking means includes a disconnecting mechanism for disengaging the coupling between the magnetic armature plate and the magnetic operating means to switch-off the switching apparatus by means of the energy accumulator. The disconnecting mechanism includes a Dshaft positioned in the interface between the armature plate and the magnetic operating means whereby rotation of the D-shaft uncouples the armature plate from the magnetic operating means. A permanent magnet and a striking pin coupled therewith cooperate with an insulating member and a second permanent magnet mounted on the opposite side of the insulating member from the first mentioned permanent magnet such that the striking pin is moved toward the insulating member to displace the second permanent magnet and rotate the D-shaft in the case of a blown fuse.

United States Patent [191 Clason Jan. 7, 1975 1 ELECTRIC SWITCHINGAPPARATUS [75] Inventor: Jan Christiaan Clason, Hengelo,

Netherlands [73] Assignee: Hazemeijer B. V., Hengelo,

Netherlands [22] Filed: Oct. 26, 1973 [21] Appl. No.: 410,025 3 O]Foreign Application Priority Data Primary ExaminerI-Iarold Broome 7]ABSTRACT In an electric switching apparatus an energy accumulatorswitches the apparatus on or off by movement of a movable member to andfrom a stationary member.

A switching-off spring associated with the energy accumulator is cockedin a switching-on state and is released with the uncoupling of amagnetic locking means mounted between the movable member and thestationary member and including magnetic operating means and an armatureplate retained by the magnetic operating means in the switched-on stateof the switching apparatus. The magnetic locking means includes adisconnecting mechanism for disengaging the coupling between themagnetic armature plate and the magnetic operating means to switch-offthe switching apparatus by means of the energy accumulator. Thedisconnecting mechanism includes a D-shaft positioned in the interfacebetween the armature plate and the magnetic operating means wherebyrotation of the D-shaft uncouples the armature plate from the magneticoperating means.

A permanent magnet and a striking pin coupled therewith cooperate withan insulating member and a second permanent magnet mounted on theopposite side of the insulating member from the first mentionedpermanent magnet such that the striking pin is moved toward theinsulating member to displace the second permanent magnet and rotate theD-shaft in the case of a blown fuse.

5 Claims, 4 Drawing Figures PATEP TED JAN 7 I575 sum u or 4 v 1 ELECTRICSWITCHING APPARATUS The invention relates to an electric switchingapparatus comprising a stationary portion and a movable portion, whichcan be moved to and from the stationary portion by means of an energyaccumulator in order to switch the switching apparatus on and off,respectively. A magnetic locking device is arranged between the movableportion and the stationary portion of the switching apparatus comprisinga magnetic system and a ferromagnetic armature plate. The armature platein the switched-on condition of the switching apparatus is retained bythe magnetic system, so that the switching apparatus is locked in itsswitched-on condition, the energy accumulator for the switching-offoperation is adapted to be charged, its stored energy being releasedupon uncoupling the locking device. Such an apparatus is known from theUS. Pat. No. 3,331,930.

The known switching apparatus is a high-voltage apparatus which iscompletely insulated by moulding resin, a number of conductors beingembedded in the stationary portion. The conductors connect cableconnecting pins projecting from the stationary portion and a number ofbus bars embedded in the stationary portion with a number of pairs ofstationary contacts, which partially project from the stationary portionand can be bridged by so-called switching caps, comprising the movableportion. The known switching apparatus is a three-phase apparatus andthus it has three pairs of stationary contacts. The pairs of stationarycontacts are arranged with respect to an axis of symmetry on the sidesof an equilateral triangle and the switching caps are coupled to apneumatic energy accumulator, so that they can be moved to and from thestationary contacts together. Furthermore, there is a magnetic lockingdevice with which the switching apparatus in its switched-on condition,in which the pairs of stationary contacts are bridged by the associatedswitching caps, is retained. In order to switch the known switchingapparatus off, a certain pneumatic pressure is gradually built up in thepneumatic cylinder by means of an air pump. As soon as the force in theswitching-off direction exerted on the movable portion of the switchingapparatus balances the retaining force of the magnetic locking device,the latter is disengaged, i.e., the armature plate is drawn away fromthe magnetic system, and the movable portion is removed from thestationary portion with high velocity. The airpump is a footoperatedpump, which is connected to the cylinder and operated by the operator,so that there is no constant pressurized air source and the energyaccumulator is normally uncharged in the switched-on condition of theswitching apparatus.

In order to cause the switch, when one or two fuses which areelectrically connected in series with the switching apparatus haveblown, to switch off as fast as possible in order to avoid an assymetricload, it is known to provide the switching apparatus with a powder gasgenerator having a powder gas cartridge, which is ignited if a fuseblows and in which the generated high-pressure gases are used forautomatically switching off the switching apparatus (see US. Pat. No.3,264,434).

The present invention has for its object to avoid the the complicationsof the application of the powder gas generator.

The invention provides an apparatus of the type described above, whichis characterized in that the magnetic locking device is provided with adisconnecting mechanism, which at its operation disengages the couplingbetween the armature plate and the magnetic system, whereafter theswitching apparatus under the influence of the continuously chargedenergy accumulator is switched off.

Thus in the apparatus according to the invention no progressivelyincreasing force in the switching-off direction is first exerted on themovable portion, which force cannot cause the switching apparatus to beswitched off until the retaining force of the magnetic locking devicewill be exceeded. In contradistinction thereto, a predetermined force inthe switching-off direction is built up first, which force does notexceed the retaining force of the magnetic locking device, whereafterthe magnetic locking device is disengaged in a mechanical way.

If according to a preferred embodiment of the invention, the energyaccumulator comprises one or more switching-off springs, which arestretched during the switching-on operation of the switching apparatus,the energy accumulator is continuously charged in the switched-oncondition of the switching apparatus, so that it is not necessary firstto charge the energy accumulator if one or more fuses have blown.

According to a preferred arrangement, the disconnecting mechanismcomprises a D-shaft, the flattened portion of which is normallypositioned in the interface between the armature plate and the magneticsystem. The rotation of the D-shaft urges the armature plate away fromthe magnetic system.

A high-voltage fuse is usually provided with a socalled striking pin,which if the fuse blows, shoots outwardly and according to the presentinvention the striking pin is coupled to a permanent magnet, which ispressed away by the striking pin and influences a second permanentmagnet through an insulating wall of the stationary portion of theswitch apparatus. The second permanent magnet is displaced thereby androtates the D-shaft. In this way an excellent electric insulationbetween the live magnet of the striking pin and the transmissionmechanism for the magnetic locking device is achieved.

The transmission mechanism between the striking pin and the D-shaft isprovided with a manual switching-off member with which the switchingapparatus can be switched off and also the transmission mechanism can bereset into the initial condition, after the blown fuses have beenreplaced.

The invention will now further be explained in reference to the annexeddrawings, in which:

FIG. 1 is a longitudinal cross-section of the electric switchingapparatus, in which only a small part of the stationary portion of theswitching apparatus is illustrated in its switched-off condition;

FIG. 2 is a cross section along line IlIl in FIG. 3, only a small part.of the movable switch being visible a larger part of the stationaryportion of the switching apparatus beingillustrated;

FIG. 3 is a side view from the left side in FIG. 2, and

FIG. 4 is a plan view as well as a cross section according to the lineIVIV in FIG. 2.

The switching apparatus comprises a stationary portion 1, formed by aninsulating moulding resin, in which a number of conductors are embedded,and a movable portion 2, mainly comprising switching caps 3, three ofwhich are present in the embodiment, but of which only one is visible inFIG. 1.

The switching caps 3 are mechanically coupled to the pneumatic drivingcylinder 4, and they can together be moved to and from the stationaryportion 1 by cylinder 4. The stationary contacts, which can be bridgedby the switch caps 3, are disposed on the stationary portion 1 in theprojections 5. For the mechanical guidance of the unit comprising thedriving cylinder 4 and the switch caps 3, three sliding shoes 6 arearranged between the three switch caps, and the sliding shoes are alsomechanically connected to the driving cylinder 4 and are capable ofsliding to-and-fro over the guiding rods 7. Between the sliding shoes 6and a projection 8 is a switching-off spring 9, which in the switched-oncondition of the switching apparatus (see FIG. 2) is stretched or drawn.In the stationary portion 1 of the switching apparatus a magnetic systemis embedded, and it comprises three permanent magnets 10. The threemagnets 10 like the three phases of the switching apparatus are arrangedsymmetrically around the axis of symmetry. In the switched-on conditionof the switching apparatus (see FIG. 2) the ferromagnetic armature plate11 arranged at the end of the pneumatic cylinder 4, is retained by themagnetic system 10. For disengaging the magnetic locking device,comprising the magnet system 10 and the armature plate 11, adisconnecting mechanism is provided which comprises a D-shaft 12,supported in two brackets 13, 14 which are partially embedded in themoulding resin 1. The D- shaft 12 has a flattened portion 15 (seeFIG. 1) which in coupled condition of the magnetic locking device liesin the interface between the pole shoes of the magnetic system 10 andthe armature plate 11 (see FIG. 2). The D-shaft 12 has at its other enda vane 16 against which an axially movable pin 17 can be pushed.

The switching apparatus has also three fuses 18, one of which is visiblein FIG. 2. Fuse 18 comprises an insulating sheath 19 and two metallicterminal contacts, of which contact 20 in FIG. 2 is provided with aswitchingoff or striking pin 22 cooperating with the permanent magnet21. Permanent magnet 21 is pushed to the left by the switching-off pin22 through the insulating disc or piston 21a, as soon as the concernedfuse 18 blows. It is observed, that the fuse 18 as well as the permanentmagnet 21 are completely insulated from the surroundings by insulatingmaterial 1. At the other end of the insulating wall 23, towards thepermanent magnet 21 is pushed, a second permanent magnet 24 is arranged,and from FIG. 3 it appears, that there are a total of three suchmagnets, which are respectively arranged at the ends of the arms of atilting lever 25. Lever 25 is rotatably supported on the pin 26. As soonas a fuse 18 blows, the permanent magnet 24 on the tilting lever 25 isrepelled or attracted according to the polarity, in the present caserepelled, by the permanent magnet 21 coupled to the striking pin 22,whereby the tilting lever 25 in FIG. 3 is rotated in clock-direction andleaves the abutment pin 27. The tilting lever 25 is provided with aprojection 28, which normally lies against a pendulum 29, which ismounted on the pivot 30. Accordingly, if the tilting lever 25 leaves theabutment pin 27 and rotates to the right in FIG. 3, the pendulum 29 isrotated in anti-clock direction across its deadpoint, whereafterpendulum 29 swings toward the abutment 31, so that the bevelled portion32 slides across the end of the pin l7 projecting from the insulatingmaterial 1 and presses pin 17. Thereby the vane 16 on the D-shaft 12 isrotated whereby the ferromagnetic armature plate 11 is urged away fromthe magnetic system 10, and the movable portion 2 of the switchingapparatus is driven into the switching-off direction under the influenceof the stretched switching-off springs 9 into the completelyswitched-offposition of FIG. 1.

In order to be able to switch-off the switching apparamechanism isenclosed inder 4. A magnetic locking device is also arranged for theswitching-on operation, and it is arranged in the end 37 of cylinder 4.This magnetic locking device, however, operates in a known way and isdisengaged automatically, as soon as the pressure in the pneumaticcylinder 4 exceeds a predetermined threshold value. The movable portion2 of the switching apparatus comprising the cylinder 4, the switchingcaps 3 and the sliding shoes 6 is arranged in a plastic cap 38.

What we claim is:

1. An electric switching apparatus, comprising:

a stationary member and a movable member;

an energy accumulator for switching the apparatus on or off by movementof said movable member to and from said stationary member, and includingat least one switching-off spring;

magnetic locking means mounted between said movable member and saidstationary member and including magnetic operating means and aferromagnetic armature plate retained by said magnetic operating meansin the switched-on state of said switching apparatus, thereby lockingsaid switching apparatus in the switched-on state;

said switching-off spring is cocked in the switchingon state and isreleased with the uncoupling of said magnetic locking means; saidmagnetic locking means including a disconnecting mechanism fordisengaging the coupling between said magnetic armature plate and saidmagnetic operating means to switch-off said switching apparatus throughsaid energy accumulator; and

said disconnecting mechanism includes a D-shaft having a flattenedportion positioned in the interface between said armature plate and saidmagnetic operating means with said switching apparatus in the on state,said D-shaft rotating to uncouple said armature plate from said magneticoperating means.

2. Apparatus as in claim 1 further comprising a fuse and means forindicating the condition of said fuse, and wherein said D-shaft iscoupled to said fuse indicating means, whereby said switching apparatusis switched off with said fuse blown.

3. Apparatus as in claim 2 wherein said fuse indicating means include afirst permanent magnet and a strik- D-shaft, whereby movement of saidfirst and second permanent magnets toward one another rotates saidtilting lever to release said pendulum to engage said pin and rotatesaid vane.

5. Apparatus as in claim 4 further comprising a manual switching-offmember coupled with said pendulum, whereby said switching apparatus isswitched-off and for rotating said pendulum to an initial position withthe replacement of a blown fuse.

1. An electric switching apparatus, comprising: a stationary member anda movable member; an energy accumulator for switching the apparatus onor off by movement of said movable member to and from said stationarymember, and including at least one switching-off spring; magneticlocking means mounted between said movable member and said stationarymember and including magnetic operating means and a ferro-magneticarmature plate retained by said magnetic operating means in theswitched-on state of said switching apparatus, thereby locking saidswitching apparatus in the switched-on state; said switching-off springis cocked in the switching-on state and is released with the uncouplingof said magnetic locking means; said magnetic locking means including adisconnecting mechanism for disengaging the coupling between saidmagnetic armature plate and said magnetic operating means to switch-offsaid switching apparatus through said energy accumulator; and saiddisconnecting mechanism includes a D-shaft having a flattened portionpositioned in the interface between said armature plate and saidmagnetic operating means with said switching apparatus in the on state,said D-shaft rotating to uncouple said armature plate from said magneticoperating means.
 2. Apparatus as in claim 1 further comprising a fuseand means for indicating the condition of said fuse, and wherein saidD-shaft is coupled to said fuse indicating means, whereby said switchingapparatus is switched-off with said fuse blown.
 3. Apparatus as in claim2 wherein said fuse indicating means include a first permanent magnetand a striking pin coupled therewith, said stationary member includes aninsulating member and a second permanent magnet mounted on the oppostieside of said insulating member from said first permanent magnet, wherebysaid striking pin is moved toward said insulating member with said fuseblown to displace said second permanent magnet and rotate said D-shaft.4. Apparatus as in claim 3 further comprising a tilting lever forsupporting said second permanent magnet, a pendulum, a pin member, and avane mounted to said D-shaft, whereby movement of said first and secondpermanent magnets toward one another rotates said tilting lever torelease said penduluM to engage said pin and rotate said vane. 5.Apparatus as in claim 4 further comprising a manual switching-off membercoupled with said pendulum, whereby said switching apparatus isswitched-off and for rotating said pendulum to an initial position withthe replacement of a blown fuse.